Internal combustion engines which are utilized to power outboard motors are commonly oriented vertically in a cowling of the motor. In this arrangement, each piston reciprocates along a horizontal axis. Each piston is connected, via a crankrod, to a vertically extending crankshaft. This crankshaft extends out the bottom of the engine in driving relation with a water propulsion device of the outboard motor.
This outboard motor engine arrangement has the advantage that the crankshaft is oriented for simple connection to a transmission or other drive for the water propulsion device. Several disadvantages are associated with this engine arrangement, however. One problem relates to the lubricating system.
As is well known, in these engines crank-bearing halves are connected to crankshaft supports extending from the cylinder block for rotatably supporting the crankshaft. Corresponding bearing halves are supported by a bearing cap connected to the cylinder block.
Oil is supplied by an oil pump from an oil pan to oil passages throughout the cylinder block of the engine. These passages include a main passage and several bearing passages leading through the crankshaft supports extending from the cylinder block for lubricating the crankshaft bearing areas. It is then intended for the lubricating oil to drain through the crankcase to the bottom of the crankcase for recovery and delivery back to the oil pan.
It has been found, however, that the lubricating oil largely becomes trapped in the bearing support areas of the bearing cap and adjacent crankcase cover. The total amount of oil available for distribution through the engine while it is running is reduced, and the oil within the crankcase may be foamed as it is thrown from the crankshaft, runs back towards the crankshaft, and is thrown from the crankshaft in repeating fashion.
In addition, the manner by which the lubricating oil is supplied to the bearing parts which support the crankshaft often greatly complicates the construction of the engine.
A lubricating system for an engine including a vertically arranged crankshaft, is desired.